Stiffening shafts for marine environments

Abstract

Described herein are examples of stiffening shafts, which in some cases are adapted to couple to a marine vessel. An exemplary stiffening shaft can be used to extend a motor from the marine vessel or be used as a shallow water stick anchor. The exemplary stiffening shafts can include a plurality of linked vertebrae stacked to form a column and at least one inelastic tension element threaded longitudinally through the plurality of vertebrae. The shaft can have a flexible configuration when the at least one tension element is released and a stiffened linear configuration when the tension element is tensed to react to torque and bending moments. Alternatively, the stiffening shaft can be used as a shallow water stick anchor for a marine vessel by piercing the bottom of a marine environment (e.g., a sea bed, a lake bed, a river bed, etc.).

What is claimed is: 
     
         1 . A stiffening shaft adapted to couple to a marine vessel, the shaft comprising:
 a plurality of vertebrae stacked to form a column; and   at least one inelastic tension element threaded longitudinally through the plurality of vertebrae to link the vertebrae,   wherein at least a portion of the shaft has a flexible configuration when the at least one tension element is released and a stiffened linear configuration when the tension element is tensed to react to torque and bending moments on the shaft.   
     
     
         2 . The stiffening shaft of  claim 1 , wherein, when the shaft transitions from the flexible configuration to the stiffened linear configuration, a first vertebra of the plurality of vertebrae attains concentric alignment with a second vertebra of the plurality of vertebrae. 
     
     
         3 . The stiffening shaft of  claim 2 , wherein the first vertebra comprises a first contoured mating surface and the second vertebra comprises a second contoured mating surface, such that, the first contoured mating surface mates with the second contoured mating surface to attain concentric alignment. 
     
     
         4 . The stiffening shaft of  claim 1 , wherein each vertebra of the plurality of vertebrae has an annular shape. 
     
     
         5 . The stiffening shaft of  claim 4 , wherein the first contoured mating surface comprises a plurality of concave surfaces arranged about a perimeter of the annular shape, and the second contoured mating surface comprises a plurality of convex surfaces arranged about the perimeter of the annular shape,
 wherein the concave and convex surfaces are adapted to mate to form a joint about which the first vertebra and the second vertebra can flex.   
     
     
         6 . The stiffening shaft of  claim 5 , wherein at least one joint forms a hole extending from the first contoured mating surface to the second contoured mating surface, wherein the hole is adapted to accept the tension element. 
     
     
         7 . The stiffening shaft of  claim 1 , wherein the at least one tension element comprises at least two tension elements, each tension element displaced from a center of the shaft. 
     
     
         8 . The stiffening shaft of  claim 1 , further comprising a motor disposed at a distal end thereof, wherein the shaft is adapted to at least partially house a control cable coupled to the motor. 
     
     
         9 . The stiffening shaft of  claim 8 , wherein the shaft is further adapted to at least partially house a power cable adapted to couple a power source with the motor. 
     
     
         10 . The stiffening shaft of  claim 1 , further comprising a tensioning system adapted to selectively tense the tension element to transition the shaft between the flexible configuration and the stiffened linear configuration. 
     
     
         11 . The stiffening shaft of  claim 10 , wherein the tensioning system is adapted to limit tension when an external force exceeding a load capacity of the shaft is applied to the shaft when the shaft is in the stiffened linear configuration. 
     
     
         12 . The stiffening shaft of  claim 1 , wherein the plurality of vertebrae include a first set of vertebrae and a second set of vertebrae, the first set of vertebrae separate from the second set of vertebrae, and
 wherein the first set and the second set zipper together to form the stiffening shaft.   
     
     
         13 . The stiffening shaft of  claim 12 , wherein a first tension element of the at least one inelastic tension element is threaded through the first set of vertebrae and a second tension element is threaded through the second set of vertebrae. 
     
     
         14 . A method of manufacturing a stiffening shaft, the method comprising the steps of:
 providing a plurality of vertebrae;   threading at least one tension element through the plurality of vertebrae to link the vertebrae; and   attaching the tension element to a tensioning system.   
     
     
         15 . The method of  claim 14 , further comprising:
 attaching a motor to an end of a column formed by the linked vertebrae.   
     
     
         16 . The method of  claim 14 , wherein each vertebra of the plurality of vertebrae comprises a first contoured mating surface and a second contoured mating surface, such that, the first contoured mating surface of a first vertebra mates with the second contoured mating surface to attain concentric alignment. 
     
     
         17 . The method of  claim 16 , wherein each vertebra of the plurality of vertebrae has an annular shape. 
     
     
         18 . The method of  claim 17 , wherein the first contoured mating surface comprises a plurality of concave surfaces arranged about a perimeter of the annular shape, and the second contoured mating surface comprises a plurality of convex surfaces arranged about the perimeter of the annular shape,
 wherein the concave and convex surfaces are adapted to mate to form a joint about which the first vertebra and the second vertebra can flex.   
     
     
         19 . The method of  claim 18 , wherein at least one joint forms a hole extending from the first contoured mating surface to the second contoured mating surface, wherein the hole is adapted to accept the tension element. 
     
     
         20 . The method of  claim 14 , wherein the at least one tension element comprises at least two tension elements, each tension element displaced from a center of the shaft. 
     
     
         21 . The method of  claim 14 , wherein the plurality of vertebrae include a first set of vertebrae and a second set of vertebrae, the first set of vertebrae separate from the second set of vertebrae, the method comprising:
 zippering the first set and the second set together to form the stiffening shaft.   
     
     
         22 . The method of  claim 21 , wherein threading at least one tension element through the plurality of vertebrae to link the vertebrae comprises:
 threading (i) a first tension element of the at least one inelastic tension element through the first set of vertebrae and (ii) a second tension element through the second set of vertebrae.   
     
     
         23 . A method of using a stiffening shaft comprising (i) a plurality of vertebrae stacked to form a column and (ii) at least one inelastic tension element threaded longitudinally through the plurality of vertebrae to link the vertebrae, wherein at least a portion of the shaft has a flexible configuration when the at least one tension element is released and a stiffened linear configuration when the tension element is tensed to react to torque and bending moments on the shaft, the method comprising:
 coupling the stiffening shaft to a marine vessel; and   stiffening the stiffening shaft to the stiffened linear configuration.   
     
     
         24 . The method of  claim 23 , wherein the stiffening shaft is coupled to a motor and the method further comprises:
 energizing the motor.   
     
     
         25 . The method of  claim 23 , further comprising:
 deploying the stiffening shaft as a stick anchor for the marine vessel.   
     
     
         26 . The method of  claim 23 , wherein the tension element is coupled to a tensioning system and wherein stiffening the stiffening shaft to the stiffened linear configuration further comprises:
 activating the tensioning system to selectively tense the tension element.   
     
     
         27 . The method of  claim 26 , wherein the tensioning system comprises a spring-loaded cam mechanism adapted to tense the tension element, and wherein activating the tensioning system comprises:
 engaging the spring-loaded cam mechanism to selectively tense the tension element.   
     
     
         28 . The method of  claim 26 , wherein the tensioning system is a hydraulically operated tensioning system adapted to tense the tension element, and wherein activating the tensioning system comprises:
 activating the hydraulically operated tensioning system to selectively tense the tension element.   
     
     
         29 . The method of  claim 23 , wherein the plurality of vertebrae include a first set of vertebrae and a second set of vertebrae, the first set of vertebrae separate from the second set of vertebrae, and wherein stiffening the stiffening shaft to the stiffened linear configuration comprises:
 zippering the first set and the second set together to form the stiffening shaft.   
     
     
         30 . The method of  claim 29 , wherein a first tension element of the at least one inelastic tension element is threaded through the first set of vertebrae and a second tension element is threaded through the second set of vertebrae.